Adding xUnit console runner for the CI

.nuget/packages.config

@@ -1,4 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
 <packages>
+  <package id="xunit.runner.console" version="2.0.0" />
   <package id="xunit.runners" version="1.9.2" />
 </packages>